1. Field of the Invention
The present invention relates generally to a rotator supporting mechanism in a microgravitational rotating apparatus performing experiments in space and more particularly to a rotator supporting mechanism comprising a bearing, such as a magnetic bearing, to thereby actively control vibrations occurring in the rotator to spread therearound.
2. Description of Related Art
FIG. 20 is a schematic plan view showing a prior art example of a rotating apparatus currently used for experiments in space. In FIG. 20, a rotating device 60, such as a motor, has four supporting members 61, 62, 63, 64 fitted thereto extending radially. Experimental boxes 70, 71, 72, 73 are fitted to respective ends of the supporting members 61–64 and experimental objects, such as plants, are contained in the experimental boxes 70–73. In the microgravitational state, the rotating apparatus is driven by the rotating device 60 to rotate at a slow speed of about 1 rotation/second. Experiments using the objects are carried out in the experimental boxes 70–73 while rotating.
In the mentioned rotating apparatus, the experimental boxes 70–73 are fitted to the ends of the supporting members 61–64, so that the end portions thereof become large in shape. Also, while the rotating apparatus itself is symmetrical around the rotating axis, the experimental objects of different kinds and different sizes are contained in the experimental boxes, and weight imbalances are caused between the experimental objects so contained. Hence, by the rotation, vibrations occur in a rotary shaft as well as in the supporting members 61–64 and the experimental boxes 70–73, thereby moving the experimental objects or otherwise negatively influencing the experiments.
In the prior art rotating apparatus used in space, as described above, vibrations (and resulting reaction forces) occur during the rotation which are transmitted to arms, like the supporting members, and the experimental boxes, that constitute a rotator, and negatively affects the experimental objects.
Also, the vibrations spread to the surrounding environment via the rotary shaft and negatively affects the surrounding space equipment and apparatus as well as the control thereof. The problems caused by such vibrations can be solved by structural means to the extent that the vibrations are steady-state vibrations that can be known beforehand. But if the vibrations accompany changes of arbitrarily occurring vibration modes, countermeasures therefor are difficult and control thereof is also limited. Thus, any countermeasures to prevent these vibrations are desired.
As mentioned above, the vibrations occurring in space are to be avoided to the extent possible and, for this purpose, studies are currently carried out so as to use an elastic bearing, such as one comprising a spring, as a bearing of the rotary shaft and also so as to suppress vibrations of the shaft by controlling exciting current of a coil in a magnetic bearing. However, an effective vibration control means has not been definitively obtained yet.